DEVELOPMENT OF THE TEETH OF OPHIDIA. 
301 
apparently been mistaken for cementum ; but a study of its development proves it clearly 
not to be such. Simultaneously with this active development of bone the base of the 
tooth-pulp, which is furnished with a layer of odontoblast cells (fig. 5), calcifies, forming 
an irregular sort of dentine, the tubes of which blend with the newly forming bone 
beneath it. The resultant conditions can be perfectly well studied in dry sections; for 
the bone of attachment differs most markedly from that of the rest of the jaw, being 
full of irregular spaces, and being stratified in a different direction (fig. 8). It adheres 
more strongly to the tooth than to the rest of the bone, so that it is often broken away 
with the former, and it must be regarded as a very rude, imperfect form of osseous 
tissue. It is apparently almost entirely absorbed when the tooth to which it belongs is 
shed, as but little trace of “ bone of attachment ” is to be seen after the loss of a 
particular tooth ; nor does a careful examination of that which serves to cement on a 
particular tooth reveal much evidence of the persistence of portions of an older date, 
although some is generally to be found by careful search. 
The poison-fangs present some peculiarities in their development which I have not 
as yet been able to fully make out, owing to the difficulty of getting poisonous snakes 
in a perfectly fresh condition. The early tooth-germs are identical with those of the 
simple teeth ; but at a later stage there is an appearance of a duct with definite walls 
within the tooth, the origin of which I have thus far failed in tracing. 
Explanation of the Plate. 
PLATE 48. 
Fig. 1. Portion of a longitudinal section of the tooth of a python with a thin, cracked 
layer of enamel. 
Fig. 2. Transverse section of the lower jaw of a common snake : to the left is seen the 
jaw-bone, with a portion of the tooth in situ upon its upper surface ; to the 
right of this is the area of tooth-development. 
a. Oral epithelium. 
b. Dentine-organ or “ papilla.” 
c. Tooth already in use. 
d. Formed dentine. 
e. Process of oral epithelium, passing in to form the enamel-organs. 
f Inner epithelium or “ enamel cells” of the enamel-organ. 
0. Layer of odontoblast cells. 
P- Parapet of fibrillated connective tissue bounding the area of tooth- 
formation on its inner side. 
1. Youngest tooth-germ, as yet only represented by the process of epithe- 
lium (e). 
2s 
MDCCCLXXV. 
